Vitreous fluorophotometry (VFP) is a clinical procedure for measuring the spatial distribution of fluorescence along the optical axis in a human subject's vitreous following administration of a fluorescent dye. In this project the clinical instrument is a Fluorotron Master manufactured by Coherent, Palo Alto, CA, and the dye is sodium fluorescein given by intravenous injection. The purpose of the project is to improve the protocols for conducting the measurements, processing the output from the instrument, and analyzing the results from the population of normal volunteers and patients. One disease for which VFP may be useful is diabetes and the associated pathology, diabetic retinopathy. The goals are to evaluate the procedure for use in 1) screening for early detection, and 2) monitoring for treatment efficiency. A pharmacokinetic mathematical model has been developed that describes the rate of appearance of fluorescein in the vitreous in terms of the blood- retinal permeability (characterized by a permeability coefficient of the retina-vitreous interface) and transport of fluorescein within the vitreous by diffusion (characterized by a diffusion coefficient). Plasma protein binding of fluorescein is also incorporated in the model.